This invention relates generally to locks and relates more particularly to locks which are used in common industrial applications, such as those used to lock desk drawers, tool boxes, vending machine cabinets or similar applications normally requiring the rotation of a locking member between two angular positions.
The class of lock to which this invention pertains includes a housing having an internal bore, a keyway cylinder supported within the bore of the housing for rotation relative to the housing, and a plurality of tumblers mounted within the cylinder for movement into and out of tumbler-accepting locking grooves provided along an inside wall of the housing. The tumblers are spring-biased toward the inside wall of the housing so that when the tumblers are received in the locking grooves, the cylinder is prevented from rotating. By fully inserting the appropriate key within the cylinder, the tumblers are moved out of the locking grooves so that the cylinder may be rotated.
A lock of the aforedescribed class can commonly be picked by inserting a picking instrument into the keyway of the cylinder to force the tumblers to an unlocked condition and simultaneously exerting a torsion force upon the cylinder. The torsion force applied to the cylinder is normally sufficient to cause each tumbler which has been manipulated out of the locking groove to an unlocked position, to frictionally catch on the inside wall of the housing so that the caught tumbler is maintained in an unlocked condition while the other tumblers are manipulated out of the locking groove. Once all of the tumblers have been caught on the inside wall of the housing, the cylinder can be turned.
It is an object of the present invention to provide a new and improved lock which possesses improved pick-resistant qualities.
Another object of the present invention is to provide such a lock which is uncomplicated in construction and effective in operation.